1. Field of the Invention
This invention relates to turbine pumps and more particularly to an improved reversible turbine pump for use in an automatic clothes washing machine.
2. Description of the Prior Art
Automatic clothes washing machines virtually always include a drain pump which is put into operation in order to effect draining of liquid from the machine after washing and rinsing operations. This pump is generally operated by the same power source, usually an electric motor, which operates the washing system of the machine so that the motor will, by reversing rotation, alternatively provide a washing action in the machine or serve to drain liquid out of the machine. An additional function which has been provided in several commercially available washing machines in recent years is recirculation of the wash liquid during the washing operation, usually for filtering purposes.
Various factors, including the ability to pass small rigid articles carried out by wash water, durability, serviceability, and the like, have led to a general trend in the washing machine industry to utilize turbine type pumps for the removal of the liquid from the machine, as opposed to centrifugal type pumps. It is well known that, with a turbine type pump, direction of flow through the pump can be reversed simply by reversing the rotation of the pump impeller, as opposed to centrifugal type pumps wherein flow necessarily is always in a generally radially outward direction through the pump.
Various types of turbine pumps have been utilized in the past in particular in connection with clothes washing machines. An example of such a turbine pump is disclosed in U.S. Pat. No. 3,127,840 issued in the name of the present inventor and assigned to the same assignee as the present invention. Examples of other turbine pumps are shown in U.S. Pat. Nos. 2,838,002; 2,883,843; 2,961,967; and 3,127,839. All of these turbine pumps have attempted to at least partially resolve the inherent problem of the pump sucking air through one of the outlet openings when the impeller is reversed. Various check valve means have been proposed including those disclosed in U.S. Pat. Nos. 2,838,002; 2,883,843; 2,961,967; 3,127,839; and 3,127,840. In these various arrangements, however, the success of preventing the pump from sucking air through one of the outlets when the liquid flow is through the other outlet has not been entirely successful primarily because of the increased power used by the pump.
By my invention I have improved the turbine pump in that by my structural arrangement the pump may be operated in either of the two directions and does not suck air through the outlet openings of the pump. Thus the efficiency of the pump is maintained and the noise resulting from sucking air through the outlet openings is eliminated. These features are highly desirable, particularly when the turbine pump is to be used in a clothes washing machine.